The Mustang's parallel valve 360 is triggered with a toothed wheel behind the ring gear, and the standard Ford sensor. I'm running an IO-390 with a mag hole trigger based on an ND reluctor, which is conceptually similar to an Electroair trigger. Both aircraft retain one magneto for now, a conservative approach to testing a new ignition system, but so far it looks like both of us will go dual eventually...already built/bought the needed parts. There are a few others following along.

A very complete EDIS/Megajolt article can be found in the British LAA magazine, August 2011. Author's name is Steve Brown. Steve apparently did quite a lot of bench testing per English homebuilding rules. I'll write something for Kitplanes in due course.

Reluctor-based systems are old tech, but work fine. Ford has sold millions of EDIS ignition units worldwide, in 4, 6, and 8 cylinder versions. They're considered very reliable, and operate independently, delivering spark at 10 BTDC if the timing computer goes on the fritz. The EDIS module can be mounted on the hot side of the firewall. However, it's just as easy to put it inside the airplane, with the Megajolt control computer, where it can live a life of luxury. In that case, there are no electronics mounted firewall forward, just the pickups (a magnet and some wire) and the coils (iron and some wire).

A late model Ford EDIS coil pack will look extremely familiar to P-mag owners. I elected to use an earlier style, just because it incorporates positive terminal retention.

I've discussed aircraft use with Brent Picasso at Autosport, who produces the little Megajolt controller. Brent is ok with experimental use, as long as everyone understands the controller was not designed or intended specifically for aircraft. The intended use is converting points-equipped fun cars to EI.

The components, leveraged as they are from automotive production numbers, are downright cheap when priced in AMU's (Aircraft Monetary Units). One of our intrepid VAF'ers bought all the Ford components for two complete ignitions at the local wrecking yard; the bill was $60. You can also buy everything new if you wish, from the usual auto parts sources. Autosport's Megajolt control units are currently $169 each, but Brent has been known to put them on sale. You'll need a laptop for setup. The software is dirt simple.

I had not intended to say much here until flying 50 hours or so; right now I'm at about 10. So, no concrete endorsement yet, although the system is working well. If you want to know more, start by downloading the Megajolt installation and operating files at:

Like everything else in EAB these days, some builders will prefer to buy a complete kit with detailed instructions, while others will happily build whatever they want. I don't expect EDIS installations to put a dent in sales at SDS, Lightspeed, or Electroair, but it certainly appears to be a viable alternative for the DIY-minded.

Just doing a little background research on the web, and MegaSquirt keeps coming up. What the difference between MegaSquirt and MegaJolt?

Simple answer: Same family tree, different branches. MegaSquirt started as an open source DIY fuel injection for everyone. At some point ignition control entered the picture as a Megasquirt function, then branched into the idea of a simple "ignition only" controller. Ultimately Autosport's principals put such a unit into production, currently known as the Megajolt/E.

Plenty of good EDIS information can be found on various Megasquirt websites (and some bad; this is, after all, the web). Be aware that Megasquirt will run a variety of different ignition schemes in addition to EDIS, as well as fuel injection.

Autosport's Megajolt/E is EDIS only.

BTW, before someone asks, no, I am not going into the ignition business. Regular readers know I do support all kinds of DIY efforts, as long as it doesn't compromise safety. Here I think the hardware/software is robust enough to fly, so the wild cards are (1) fabrication skill, and (2) installation details like wire routing, connector selection, and software settings. If you have the skills, go for it. If you don't, there is no shame in buying a CPI kit from Ross at SDS: http://www.sdsefi.com/cpi.htm

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